Polysilsesquioxane aerogel material, preparation method, application and detection method

Abstract

The invention provides a polysilsesquioxane aerogel material, a preparation method, application and a detection method, and belongs to the technical field of water quality detection. In order to solve the problem that an existing method for enriching and detecting geosmin and 2-methylisoborneol in water is expensive, the invention provides a polysilsesquioxane aerogel material for detection, and a preparation method of the polysilsesquioxane aerogel material for detection comprises the following steps: 1) mixing trialkoxymethylsilane and 3, 3, 3-trifluoropropyltrialkoxysilane to obtain gel; 2) carrying out solvent replacement on the gel; and 3) drying at normal pressure to obtain the aerogel material. The aerogel material is prepared by adopting a method of acid-base catalysis and step-by-step normal-pressure drying, so that the high cost of supercritical drying or freeze drying is saved. The prepared aerogel material has a functional side chain, a larger specific surface area and higher chemical stability and thermal stability, and compared with commercial solid-phase microextraction, the limit of quantitation can be reduced by more than one time, and the aerogel material has higher detection sensitivity.

Description

Technical Field

[0001] This invention belongs to the field of water quality testing technology, specifically relating to a polysilsesquioxane aerogel material, its preparation method, its application, and its testing method. Background Technology

[0002] Aerogel materials are nanoporous lightweight materials containing nanoscale pore structures (1-100 nm) and possessing extremely large specific surface areas (200-1000 m²). 2 / g), very high porosity (80-99.8%), very low density (1-500kg / m³) 3 With its characteristics such as high molecular weight polysilsesquioxane (PHMS) and very low thermal conductivity (0.02 W / m·K), PHMS has wide applications in optics, electronics, acoustic impedance, and thermal insulation. PHMS is a class of organic-inorganic hybrid silicon-based polymer materials. Using PHMS precursors as the core raw material, it undergoes acid-base catalytic hydrolysis and condensation to form a gel, followed by drying to obtain PHMS aerogel. The addition of PHMS as a functional component endows this aerogel material with hydrophobicity and functionality, exhibiting stronger adsorption and selectivity in the adsorption field.

[0003] Odor-causing substances in drinking water include microbial metabolites such as geosmin and 2-methylisoborneol, with extremely low odor threshold concentrations, approximately 10 ng / L. Gas chromatography-mass spectrometry (GC-MS) is an effective method for analyzing trace organic matter, capable of quantitative analysis of volatile and semi-volatile organic compounds. It is currently the only technique capable of qualitative and quantitative analysis of odor-causing substances in water. The key lies in sample pretreatment techniques, specifically enriching trace organic matter to improve detection sensitivity. Solid-phase microextraction (SPME) is a commonly used method for enriching trace organic matter; however, the use of some commercially available coatings is greatly limited due to their high cost and limited recycling rates. Therefore, there is a need to find more efficient adsorption materials to enrich geosmin and 2-methylisoborneol in water.

[0004] Functionalized polysilsesquioxane aerogel materials have high adsorption rates, repeatability, and regenerability, and can be used to enrich trace amounts of geosmin and 2-methylisoborneol in water, thereby improving detection sensitivity. Summary of the Invention

[0005] The purpose of this invention is to provide a polysilsesquioxane aerogel material, its preparation method, application, and detection method, so as to achieve the enrichment and detection of trace amounts of geosmin and 2-methylisoborneol in water.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A method for preparing a polysilsesquioxane aerogel material includes the following steps: 1) Mix trialkoxymethylsilane and 3,3,3-trifluoropropyltrikoxysilane, add hydrochloric acid solution, stir thoroughly, then add ammonia water and stir thoroughly to obtain polysilsesquioxane gel; 2) Solvent displacement was performed on the polysilsesquioxane gel; 3) The polysilsesquioxane gel that has undergone solvent replacement is dried under normal pressure to obtain an aerogel material.

[0007] Trialkoxymethylsilane is methyltrimethoxysilane or methyltriethoxysilane; 3,3,3-trifluoropropyltrialkoxysilane is 3,3,3-trifluoropropyltriethoxysilane or 3,3,3-trifluoropropyltrimethoxysilane.

[0008] The volume ratio of trialkoxymethylsilane to 3,3,3-trifluoropropyltrialkoxysilane is 10:1 to 1:4. Solvent replacement of polysilsesquioxane gel was performed using ethanol.

[0009] During solvent replacement, ethanol is added to the polysilsesquioxane gel, and after standing for 8-12 hours, the ethanol is discarded. This process is repeated 4-6 times.

[0010] Atmospheric pressure drying adopts a step-by-step drying method. First, the temperature is raised to 50-80℃ and dried for 1-3 hours, and then the temperature is raised to 100-200℃ and dried for 2-4 hours.

[0011] The heating rate is 5-10℃ / min.

[0012] The present invention also provides a polysilsesquioxane aerogel material, which is obtained by the aforementioned preparation method.

[0013] This invention also provides an application of polysilsesquioxane aerogel material for preparing adsorbent materials that adsorb geosmin and / or 2-methylisoborneol in water.

[0014] This invention also provides an application of polysilsesquioxane aerogel material for preparing an adsorption device for detecting geosmin and / or 2-methylisoborneol in water. The polysilsesquioxane aerogel material is ground and then filled into an adsorption tube, and both ends of the adsorption tube are sealed with glass wool to obtain the adsorption device.

[0015] After grinding the polysilsesquioxane aerogel material, a 60-80 mesh portion was collected and loaded into an adsorption tube.

[0016] The adsorption tube is a gas chromatograph liner, a stainless steel straight tube, or a stainless steel U-shaped tube.

[0017] The inner diameter of the adsorption tube is 1.5-4.0 mm.

[0018] The gas chromatograph liner is 80mm long, the stainless steel straight tube is 130mm long, and the stainless steel U-tube is 310mm long.

[0019] The amount of polysilsesquioxane aerogel material loaded in the adsorption tube is 50-500 mg.

[0020] This invention also provides a method for detecting geosmin and 2-methylisoborneol in water. The method involves preparing an adsorbent material using the aforementioned polysilsesquioxane aerogel material, filling the aerogel material into an adsorption tube, sealing both ends of the adsorption tube with glass wool, connecting the adsorption tube to an adsorption device, adding a water sample to the adsorption device, and after a set adsorption time, removing the adsorption tube and placing it in a thermal desorption-GC-MS coupled device to detect geosmin and 2-methylisoborneol.

[0021] After the test is completed, the adsorption tube is placed on the aging equipment for aging. After aging, the adsorption tube can be reused.

[0022] The adsorption tubes were aged at 280°C.

[0023] The adsorption tubes are heated in an aging device at a rate of 10°C / min from room temperature to 280°C for 300 minutes before being reused. The adsorption tubes can be reused by aging at 280°C.

[0024] The above-described solution of the present invention has at least the following beneficial effects: 1) The method of the present invention uses polysilsesquioxane as the core aerogel material and adopts an acid-base catalysis and stepwise atmospheric pressure drying preparation method, which eliminates the complex preparation process and expensive preparation cost of supercritical drying or freeze drying.

[0025] 2) The polysilsesquioxane aerogel material prepared by this invention possesses functional side chains, a large specific surface area, and high chemical and thermal stability. The specific surface area is 600-1000 m². 2 / g.

[0026] 3) This invention employs a gas chromatograph liner, a stainless steel U-tube, or a stainless steel straight tube to fill with polysilsesquioxane aerogel material to prepare an adsorption device. This adsorption device has a simple structure, low cost, and is easy to use. When used in conjunction with thermal desorption-gas chromatography-mass spectrometry, it can detect geosmin and 2-methylisoborneol in water at a lower cost. Furthermore, under the same water sample concentration conditions (geosmin 0.01 ng / ml and 2-methylisoborneol 0.01 ng / ml), compared with commercial solid-phase microextraction, the detection limit is more than half lower, exhibiting higher detection sensitivity. Attached Figure Description

[0027] Figure 1 This is a TEM image of the polysilsesquioxane aerogel material of the present invention.

[0028] Figure 2 This is a nitrogen adsorption diagram of the polysilsesquioxane aerogel material of the present invention.

[0029] Figure 3 This is a diagram of the adsorption device in Example 1.

[0030] Figure 4 This is a diagram of the adsorption device in Example 2.

[0031] Figure 5 This is a diagram of the adsorption device in Example 3.

[0032] Figure 6 This is a schematic diagram of the structure of the polysilsesquioxane aerogel material adsorption device of the present invention.

[0033] Figure 7 This is the total ion chromatogram of geosmin and 2-methylisoborneol in the detection method of the present invention.

[0034] Figure 8 This is the extracted ion mass spectrum of 2-methylisocamphenol in the detection method of the present invention.

[0035] Figure 9 This is the extracted ion mass spectrum of geosmin in the detection method of this invention.

[0036] Figure 10 This is a chromatographic comparison of 2-methylisoborneol using the detection method of this invention and the solid-phase microextraction detection method.

[0037] Figure 11 This is a chromatographic comparison of geosmin detection using the detection method of this invention and the solid-phase microextraction detection method. Detailed Implementation

[0038] Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0039] The preparation method of the polysilsesquioxane aerogel material of the present invention is as follows: 1) Mix trialkoxymethylsilane and 3,3,3-trifluoropropyltrikoxysilane, add hydrochloric acid at a concentration of 0.01%-1% (v / v), stir thoroughly at room temperature for 20-40 minutes, then add ammonia at a concentration of 25%-50% (v / v), stir thoroughly at room temperature for 5-15 minutes to obtain polysilsesquioxane gel, and let it stand overnight; 2) Add ethanol to the above gel, let it stand for 8-12 hours, then discard the ethanol. Repeat this solvent replacement process 4-6 times. 3) The solvent-displaced gel was dried in steps under normal pressure. The temperature was increased to 50-80℃ at a rate of 5-10℃ / min, and dried for 1-3 hours. Then, the temperature was increased to 100-200℃ and dried for 2-4 hours to obtain the aerogel material. The microstructure of the aerogel material is visible. Figure 1 . Example 1

[0040] A method for preparing polysilsesquioxane aerogel material is as follows: 1 ml of methyltrimethoxysilane and 0.1 ml of 3,3,3-trifluoropropyltriethoxysilane are mixed, followed by the addition of 0.3 ml of dilute hydrochloric acid solution. The mixture is vortexed at room temperature for 20 min, then 0.05 ml of ammonia is added, and the mixture is vortexed at room temperature for 5 min to form a gel. The gel is then allowed to stand overnight. Solvent replacement is performed four times with ethanol, with each addition followed by 8 h of standing. After solvent replacement, the temperature is increased to 80°C at a rate of 5°C / min and dried at 80°C for 1 h. The temperature is then increased to 200°C at a rate of 5°C / min and dried at 200°C for 2 h to obtain the polysilsesquioxane aerogel material. The aerogel material is ground, and the 60-80 mesh fraction is collected. On an aging device, the temperature is increased from room temperature to 280°C at a rate of 10°C / min and maintained for 300 min for later use.

[0041] The aforementioned polysilsesquioxane aerogel material was then used to prepare an adsorbent material for adsorbing geosmin and / or 2-methylisoborneol in water.

[0042] To utilize the properties of polysilsesquioxane aerogel, it was prepared as an adsorption device for adsorbing geosmin and / or 2-methylisoborneol from water. Specifically, the aerogel material was filled into a stainless steel U-tube with an inner diameter of 1.5 mm and a length of 310 mm, with a loading of 500 mg. Both ends were sealed with glass wool. The adsorption device is as follows: Figure 3 As shown. Example 2

[0043] A method for preparing polysilsesquioxane aerogel material is as follows: 1 ml of methyltriethoxysilane and 4 ml of 3,3,3-trifluoropropyltrimethoxysilane are mixed, then 1.5 ml of dilute hydrochloric acid solution is added, and the mixture is vortexed at room temperature for 40 min. Then, 0.2 ml of ammonia water is added, and the mixture is vortexed at room temperature for 15 min to form a gel. The gel is allowed to stand overnight, and the solvent is replaced with ethanol 6 times, with each addition of ethanol followed by 12 h of standing. After the ethanol replacement is completed, the temperature is increased to 50℃ at a rate of 10℃ / min, and dried at 50℃ for 3 h. Then, the temperature is increased to 100℃ at a rate of 5℃ / min, and dried at 100℃ for 4 h to obtain the polysilsesquioxane aerogel material. The aerogel material is ground, and the 60-80 mesh fraction is collected. On an aging device, the temperature is increased from room temperature to 280℃ at a rate of 10℃ / min and held for 300 min for later use.

[0044] The aforementioned polysilsesquioxane aerogel material was then used to prepare an adsorbent material for adsorbing geosmin and / or 2-methylisoborneol in water.

[0045] To utilize the properties of polysilsesquioxane aerogel, it was prepared as an adsorption device for adsorbing geosmin and / or 2-methylisoborneol from water. Specifically, the aerogel material was filled into a stainless steel straight tube with an inner diameter of 3 mm and a length of 130 mm, with a filling amount of 100 mg. Both ends were sealed with glass wool. The adsorption device is as follows: Figure 4 As shown. Example 3

[0046] A method for preparing polysilsesquioxane aerogel material is as follows: 1.2 ml of methyltrimethoxysilane and 1.5 ml of 3,3,3-trifluoropropyltrimethoxysilane are mixed, then 1 ml of dilute hydrochloric acid solution is added, and the mixture is vortexed at room temperature for 30 min. Then, 0.1 ml of ammonia water is added, and the mixture is vortexed at room temperature for 10 min to form a gel. The gel is then allowed to stand overnight. The solvent is replaced with ethanol five times, with each addition of ethanol followed by 10 h of standing. After the ethanol replacement is completed, the temperature is increased to 80℃ at a rate of 10℃ / min and dried at 80℃ for 2 h. Then, the temperature is increased to 150℃ at a rate of 10℃ / min and dried at 150℃ for 3 h to obtain the polysilsesquioxane aerogel material. The aerogel material is ground, and the 60-80 mesh fraction is collected. On an aging device, the temperature is increased from room temperature to 280℃ at a rate of 10℃ / min and held for 300 min for later use.

[0047] The aforementioned polysilsesquioxane aerogel material was then used to prepare an adsorbent material for adsorbing geosmin and / or 2-methylisoborneol in water.

[0048] To utilize the properties of polysilsesquioxane aerogel, it was prepared as an adsorption device for adsorbing geosmin and / or 2-methylisoborneol from water. Specifically, the aerogel material was packed into a gas chromatograph liner with an inner diameter of 4 mm, a length of 80 mm, and a loading of 80 mg. Both ends were sealed with glass wool. The adsorption device is as follows: Figure 5 As shown. Example 4: The specific surface area of ​​the prepared adsorption device was measured using aerogel material.

[0049] The specific surface area of ​​the aerogel material of this invention was determined by nitrogen adsorption. The testing instrument was a Quantachrome ASiQwin fully automated specific surface area and porosity analyzer, and the testing conditions were as follows: degassing temperature: 200℃, degassing time: 6h; adsorbate: high-purity nitrogen (purity ≥99.999%); testing temperature: liquid nitrogen temperature (77K).

[0050] Then, the multi-point BET method is used, at relative pressure P / P o The specific surface area was calculated within the range of 0.04–0.30, and its multi-point BET linear fitting plot is shown below. Figure 2 As shown, the fitting parameters are: Slope: 5.017 1 / g, Intercept: 6.620 × 10⁻⁶. -2 1 / g, correlation coefficient r: 0.999278, BET constant (C constant): 76.788. As shown in the figure, within the tested relative pressure range, the BET linear fitting correlation coefficient r is 0.999278, indicating a good linear relationship. The final obtained BET specific surface area of ​​the material is 685.04 m² / g. Example 5: Method of using the adsorption devices of Examples 1, 2, and 3 (water sample testing method)

[0051] 1) Take a reagent bottle 8 containing a water sample. The bottle cap has a two-way reactor connector. One connector is connected to the adsorption device 5 (adsorption tube) of Examples 1, 2, and 3 above with a screw using a PEEK tube 9, ensuring a seal. The other connector is connected to the nitrogen delivery unit using a PEEK tube 9, introducing nitrogen into the reagent bottle. The reagent bottle 8 is placed on a water bath heated magnetic stirrer 7, and the magnetic stir bar 6 is placed in the reagent bottle 8. Agitation and pneumatic adsorption are performed at 55℃~65℃ for 50~60 minutes. The nitrogen delivery unit includes a nitrogen source, a flow meter 1, a needle valve 2, a pressure regulating valve 3, and a pressure gauge 4 connected sequentially through pipelines. The adsorption equipment includes the reagent bottle 8, the nitrogen delivery unit, and the water bath heated magnetic stirrer 7, as shown below. Figure 6 As shown.

[0052] 2) After the pneumatic adsorption is completed, the adsorption device 5 is removed and desorbed at 200-280℃, and then detected by GC-MS.

[0053] The adsorption-desorption-detection results of geosmin and 2-methylisoborneol in water are as follows: Figure 7 , 8 As shown in Figure 9, Figure 7 The total ion chromatogram showed two clear characteristic peaks at retention times of 13.681 min and 14.861 min, respectively. The peaks were symmetrical and free of interference from other peaks. The mass spectra corresponding to the two peaks were extracted. Figure 8 The characteristic ions of the 13.681 min peak are consistent with the standard mass spectrometry characteristics of 2-methylisoborneol (2-MIB); Figure 9 The characteristic ions at the 14.861 min peak match the standard mass spectrometry characteristics of geosmin (GSM), indicating that the substances enriched by the aerogel material of the present invention are geosmin (GSM) and 2-methylisoborneol (2-MIB).

[0054] 3) The materials in the adsorption device are aged at 280℃ and reused. Example 6: Comparison of adsorption and desorption of the adsorption material of the present invention with commercially available solid-phase microextraction materials

[0055] Take 100 ml of water sample containing geosmin and 2-methylisoborneol (gesmin 0.01 ng / ml and 2-methylisoborneol 0.01 ng / ml), and connect a stainless steel straight tube filled with polysilsesquioxane aerogel material (the adsorption device of Example 2) to the adsorption equipment (see [reference]). Figure 6 (As in Example 5), after adsorption at 60°C for 50 min, the stainless steel straight tube was removed and desorbed at 280°C in a thermal desorption-GC-MS coupled apparatus. Then, GC-MS was used to detect geosmin and 2-methylisoborneol.

[0056] Take 40 ml of water sample containing geosmin and 2-methylisoborneol (0.01 ng / ml geosmin and 0.01 ng / ml 2-methylisoborneol) into an extraction flask, insert commercial solid-phase microextraction material (DVB / CAR / PDMS), and adsorb at 60 °C for 45 min. Remove the solid-phase microextraction material, insert it into the gas chromatograph inlet, and desorb at 280 °C. Then, detect geosmin and 2-methylisoborneol by GC-MS.

[0057] The detection results of the method of the present invention and the detection results of solid phase microextraction are superimposed for comparison, for example... Figure 10-11 As shown, Figure 10 The left half shows 2-methylisoborneol enriched by solid phase microextraction (SPME), with an abundance of less than 5000, while the right half shows 2-methylisoborneol enriched by the detection method of the present invention, with an abundance of about 48000. Figure 11The left half shows that the abundance of geosmin enriched by solid phase microextraction (SPME) is less than 20,000, while the right half shows that the abundance of geosmin enriched by the detection method of the present invention reaches 44,000.

[0058] As can be seen from the above comparison, the polysilsesquioxane aerogel material prepared in this invention has a lower limit of quantification (LOQ) for geosmin and 2-methylisoborneol than that for solid-phase microextraction, under the same water sample concentration conditions (geosmin 0.01 ng / ml and 2-methylisoborneol 0.01 ng / ml), thus achieving higher detection sensitivity.

[0059] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones. All modifications within the scope of this invention, or equivalent modifications within the scope of this invention, are included in this invention.

Claims

1. A method for preparing a polysilsesquioxane aerogel material, characterized in that, Includes the following steps: 1) Mix trialkoxymethylsilane and 3,3,3-trifluoropropyltrikoxysilane, add hydrochloric acid solution, stir thoroughly, then add ammonia water and stir thoroughly to obtain polysilsesquioxane gel; 2) Solvent displacement was performed on the polysilsesquioxane gel; 3) The polysilsesquioxane gel that has undergone solvent replacement is dried under normal pressure to obtain an aerogel material.

2. The method for preparing the polysilsesquioxane aerogel material according to claim 1, characterized in that, The volume ratio of trimekoxymethylsilane to 3,3,3-trifluoropropyltrikeoxysilane is 10:1 to 1:

4.

3. The method for preparing the polysilsesquioxane aerogel material according to claim 1, characterized in that, Trialkoxymethylsilane is methyltrimethoxysilane or methyltriethoxysilane; 3,3,3-trifluoropropyltrialkoxysilane is 3,3,3-trifluoropropyltriethoxysilane or 3,3,3-trifluoropropyltrimethoxysilane.

4. The method for preparing the polysilsesquioxane aerogel material according to claim 1, characterized in that, Solvent replacement of polysilsesquioxane gel was performed using ethanol.

5. The method for preparing the polysilsesquioxane aerogel material according to claim 1, characterized in that, Atmospheric pressure drying adopts a step-by-step drying method. First, the temperature is raised to 50-80℃ and dried for 1-3 hours, and then the temperature is raised to 100-200℃ and dried for 2-4 hours.

6. A polysilsesquioxane aerogel material, characterized in that, It is obtained by the preparation method described in any one of claims 1-5.

7. An application of the polysilsesquioxane aerogel material according to claim 6, characterized in that, This material is used to prepare adsorbents for adsorbing geosmin and / or 2-methylisoborneol in water.

8. An application of the polysilsesquioxane aerogel material according to claim 6, characterized in that, To prepare an adsorption device for detecting geosmin and / or 2-methylisoborneol in water, polysilsesquioxane aerogel material is ground and filled into an adsorption tube, and both ends of the adsorption tube are sealed with glass wool to obtain the adsorption device.

9. The application according to claim 8, characterized in that, The adsorption tube is a gas chromatograph liner, a stainless steel straight tube, or a stainless steel U-shaped tube.

10. A method for detecting geosmin and 2-methylisoborneol in water, characterized in that, An adsorbent material was prepared using the polysilsesquioxane aerogel material as described in claim 5. The polysilsesquioxane aerogel material was filled into an adsorption tube, and both ends of the adsorption tube were sealed with glass wool. The adsorption tube was connected to an adsorption device, and a water sample was added to the adsorption device. After the adsorption was performed for a set time, the adsorption tube was removed and placed in a thermal desorption-GC-MS coupled device to detect geosmin and 2-methylisoborneol.

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